title: An ungrouped plant kinesin accumulates at the preprophase band in a cell cycle-dependent manner.
abstract: Past phylogenic studies have identified a plant-specific, ungrouped family of kinesins in which the motor domain does not group to one of the fourteen recognized families. Members of this family contain an N-terminal motor domain, a C-terminal armadillo repeat domain and a conserved destruction box (D-BOX) motif. This domain architecture is unique to plants and to a subset of protists. Further characterization of one representative member from Arabidopsis, Arabidopsis thaliana KINESIN ungrouped clade, gene A (AtKINUa), was completed to ascertain its functional role in plants. Fluorescence confocal microscopy revealed an accumulation of ATKINUA:GFP at the preprophase band (PPB) in a cell cycle-dependent manner in Arabidopsis epidermal cells and tobacco BY-2 cells. Fluorescence accumulation was highest during prophase and decreased after nuclear envelope breakdown. A conserved D-BOX motif was identified through alignment of AtKINU homologous sequences. Mutagenesis work with D-BOX revealed that conserved residues were necessary for the observed degradation pattern of ATKINUA:GFP, as well as the targeted accumulation at the PPB. Overall results suggest that AtKINUa is necessary for normal plant growth and/or development and is likely involved with PPB organization through microtubule association and specific cell cycle regulation. The D-BOX motif may function to bridge microtubule organization with changes that occur during progression through mitosis and may represent a novel regulatory motif in plant microtubule motor proteins.
authors.affiliation: Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania, USA.
authors.forename: Jennelle L
authors.initials: JL
authors.lastname: Malcos
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cyr
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D019295:Computational Biology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D016547:Kinesins / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D011418:Prophase; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins; D016547:Kinesins